I doubt it. it will still be cheaper than government pot. Just like the bootleg booze and cigarettes are. that illegal industry is still quite large.
It's not called the Burrough(?) of alcohol, firearms and tobacco for nothing you know.
The black market in booze is not large enough to sustain the cartels. There is virtually no black market in cigarettes in low-tax states.
An underground market simply cannot compete with a well regulated and reasonably taxed market like alcohol. Same would be true for marijuana. It's economics 101.